Abstract:
This biomechanics paper introduces and validates a novel deformable image registration technique called Hyperelastic Warping for measuring left ventricular (LV) strain during systole using non-tagged cine-MRI images. The objective was to overcome the limitations of traditional methods like tagged MRI, which suffer from limited resolution and tag fading. The Hyperelastic Warping approach combines high-resolution non-tagged MRI data with a detailed computational model that incorporates myocardial material properties, fiber direction, and active fiber contraction. This model accounts for the complex biomechanics of systolic contraction, which is more challenging to model than passive diastolic filling. The study validated the technique by comparing its predictions for circumferential and radial strains with those from tagged MRI images analyzed with a Harmonic Phase (HARP) algorithm. The results showed a strong correlation between the two methods, with R² values of 0.75 for circumferential strain and 0.78 for radial strain. Additionally, the paper performed sensitivity studies to evaluate the impact of various computational and material parameters, concluding that the best predictions were achieved using a slightly compressible hyperelastic model and a physiologically realistic helical fiber distribution. The biomechanical insights from this study provide a unique alternative for high-resolution, regional quantification of myocardial deformation and contractile function without the need for MRI tagging.
